CNS and PNS

Central Nervous System (CNS)

CNS consists of brain and spinal cord

Adult Brain Regions1. Brain stem (midbrain, pons, and medulla)

2. Cerebellum

3. Diencephalon

4. Cerebral hemispheres

Cerebralhemisphere

Diencephalon

Cerebellum

Brain stem• Midbrain• Pons• Medulla oblongata

Brain Stem

Three regions Midbrain Pons Medulla oblongata

Lateral ventricle(covered by septumpellucidum)

Third ventricle

Anterior commissure

Hypothalamus

Corpus callosumFornix

Thalamus

PosteriorcommissurePineal gland

Corporaquadrigemina

Cerebralaqueduct

Midbrain

Arbor vitae

Fourth ventricle

Cerebellum

Medulla oblongata

Pons

Optic chiasma

Epithalamus

Mammillary body

Brain StemControls automatic behaviors necessary for

survival Breathing Circulation Digestion Swallowing

Frontal lobe

Olfactory bulb(synapse point ofcranial nerve I)

Optic nerve (II)

Optic chiasma

Optic tract

Mammillary body

Midbrain

Pons

Temporallobe

Medullaoblongata

Cerebellum

Spinal cord

MidbrainAssociated with vision, hearing,

motor control, sleep/wake, arousal (alertness), and temperature regulation.

Substantia nigra—functionally linked to basal nuclei

TectumPeriaqueductal gray matterOculomotor nucleus (III)

Dorsal

Medial lemniscusRed nucleusSubstantianigraFibers ofpyramidal tract

Superiorcolliculus

Cerebral aqueduct

Reticular formation

Crus cerebri of cerebral peduncle

Ventral

Midbrain

PonsFibers of pons

Connect higher brain centers and spinal cord

Nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with

sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.

Superior cerebellar peduncleTrigeminalmain sensorynucleusTrigeminal motor nucleusMiddle cerebellarpeduncleTrigeminalnerve (V)Medial lemniscus

Fourthventricle

Reticularformation

Pontine nuclei

Fibers of pyramidaltractPons

Medulla Oblongata: FunctionsCardiovascular center

Cardiac center adjusts force and rate of heart contraction

Respiratory centers Generate respiratory rhythm Control rate and depth of breathing (with pontine

centers)

Medulla OblongataAdditional centers regulate

Vomiting Hiccuping Swallowing Coughing Sneezing

Cerebellum Input from cortex, brain stem and sensory

receptors

Allows smooth, coordinated movements Learn to ride a bicycle

Anterior lobeArbor vitae

Cerebellar cortex

Pons

Fourth ventricle

Medulla oblongata

Posterior lobe

Flocculonodular lobeChoroid plexus

AnteriorlobePrimaryfissure

Posteriorlobe

Horizontalfissure

Vermis Vermis

Cerebellar Processing of Motor ActivityCerebellum receives impulses

from cerebral cortex of intent to initiate voluntary muscle contraction

Continuously "inform" cerebellum of body's position and momentumProprioception

Smoothly coordinate muscle contraction

Basal Nuclei (Ganglia)Caudate nucleus

Putamen

Globus pallidus

CaudatenucleusPutamen

Striatum Thalamus

Tail of caudatenucleus

Cerebral cortex

Cerebral white matter

Corpus callosum

Anterior hornof lateral ventricle

PutamenGlobus pallidus

Thalamus

Third ventricle

Inferior hornof lateral ventricle

Head of caudate nucleus

Tail of caudate nucleus

Anterior

Posterior

Functions of Basal NucleiFunctions thought to be

Helps in balance

Diencephalon Thalamus Hypothalamus Epithalamus

Cerebral hemisphere

Septum pellucidum

Interthalamicadhesion(intermediatemass of thalamus)

InterventricularforamenAnteriorcommissureHypothalamusOptic chiasma

Pituitary glandMammillary bodyPonsMedulla oblongataSpinal cord

Corpus callosum

Fornix

Choroid plexus

Thalamus(encloses third ventricle)

PosteriorcommissurePineal gland

Epithalamus

CorporaquadrigeminaCerebralaqueduct

Midbrain

Arbor vitae (of cerebellum)Fourth ventricleChoroid plexusCerebellum

Thalamic Function“Router” to cerebral cortex

Sorts, edits, and relays ascending input

HypothalamusUnderneath the Thalamus

Contains many nuclei

AnteriorcommissurePreopticnucleusAnteriorhypothalamicnucleusSupraopticnucleusSuprachiasmaticnucleus

OpticchiasmaInfundibulum(stalk of thepituitary gland)

Paraventricularnucleus

FornixDorsomedialnucleus

PosteriorhypothalamicnucleusLateralhypothalamicarea

VentromedialnucleusMammillarybody

ArcuatenucleusPituitarygland

The main hypothalamic nuclei.

Hypothalamic FunctionControls autonomic nervous system (e.g.,

blood pressure, rate and force of heartbeat, digestive tract motility, pupil size)

Physical responses to emotions (limbic system) Perception of pleasure, fear, and rage, and in

biological rhythms and drives

Hypothalamic FunctionRegulates sleep-wake cycles

Controls endocrine system Controls secretions of anterior pituitary gland Produces posterior pituitary hormones

Hypothalamic FunctionRegulates body temperature –

sweating/shivering

Regulates hunger and satiety in response to nutrient blood levels or hormones

Regulates water balance and thirst

Cerebral hemisphere

Septum pellucidum

Interthalamicadhesion(intermediatemass of thalamus)

InterventricularforamenAnteriorcommissureHypothalamusOptic chiasma

Pituitary glandMammillary bodyPonsMedulla oblongataSpinal cord

Corpus callosum

Fornix

Choroid plexus

Thalamus(encloses third ventricle)

PosteriorcommissurePineal gland

Epithalamus

CorporaquadrigeminaCerebralaqueduct

Midbrain

Arbor vitae (of cerebellum)Fourth ventricleChoroid plexusCerebellum

EpithalamusConnect the limbic system to other parts of the

brain Regulation of emotions

Pineal gland secretes melatonin Involved in circadian rhythms

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Lateral ventricle(covered by septumpellucidum)

Third ventricle

Anterior commissure

Hypothalamus

Corpus callosumFornix

Thalamus

PosteriorcommissurePineal gland

Corporaquadrigemina

Cerebralaqueduct

Midbrain

Arbor vitae

Fourth ventricle

Cerebellum

Medulla oblongata

Pons

Optic chiasma

Epithalamus

Mammillary body

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Lateralization of Cortical FunctionLeft hemisphere

Controls language, math, and logic

Right hemisphere Visual-spatial skills, intuition, emotion, and artistic

and musical skills

Hemispheres communicate almost instantaneously via fiber tracts and functional integration

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Cerebral HemispheresFive lobes

Frontal Parietal Temporal Occipital Insula

Cerebral CortexThin (2–4 mm) superficial layer of gray matter

40% mass of brain

Site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding

4 General Considerations of Cerebral Cortex1. Three types of functional areas

Motor areas—control voluntary movement Sensory areas—conscious awareness of sensation Association areas—integrate diverse information

2. Each hemisphere concerned with contralateral side of body

Cerebral HemispheresCentral sulcus

Separates precentral gyrus of frontal lobe and postcentral gyrus of parietal lobe

Frontal lobe

Postcentralgyrus

Parietal lobe

CentralsulcusPrecentral

gyrus

Parieto-occipital sulcus(on medial surfaceof hemisphere)

Lateral sulcus

Temporal lobeOccipital lobe

Transversecerebral fissure

Pons

Spinal cordFissure(a deepsulcus)

Gyrus

Cortex (gray matter)

Sulcus

White matter

Lobes and sulci of the cerebrum

Medulla oblongata

Cerebellum

Primary Motor Cortex

Motor homunculi - upside-down caricatures represent contralateral motor innervation of body regions

Frontal lobeCentralsulcus

Gyri of insula

Temporal lobe(pulled down)

Location of the insula lobe

Posterior

Motor SensoryAnterior

Primary motorcortex(precentral gyrus)

Primary somato-sensory cortex(postcentral gyrus)

Motor map inprecentral gyrus

Sensory map inpostcentral gyrus

Swallowing

Tongue

Jaw

Lips

Face

Eye

Brow

Neck

Thumb

Fingers

Hand

Elb

ow

Wrist

Toes

Genitals

Arm

Sh

ou

lder

Tru

nk

Hip

Fo

ot

Kn

ee

Kn

ee

Leg Hip

Tru

nk

Ne

ck

Hea

dA

rmE

lbow

Fore

arm

Han

d

Fing

ers

Thum

b

Eye

Nose

Face

Lips

Teeth

JawGums

Tongue

Pharynx

Intra-abdominal

Primary Somatosensory Cortex

In postcentral gyri of parietal lobe

Receives general sensory information Somatosensory homunculus upside-down caricatures represent contralateral sensory input from body regions

Posterior

SensoryAnterior

Primary somato-sensory cortex(postcentral gyrus)

Sensory map inpostcentral gyrus

Genitals

Fo

ot

Kn

ee

Leg Hip

Tru

nk

Ne

ck

Hea

dA

rmE

lbow

Fore

arm

Han

d

Fing

ers

Thum

b

Eye

Nose

Face

Lips

Teeth

JawGums

Tongue

Pharynx

Intra-abdominal

Visual AreasPrimary visual (striate) cortex

Extreme posterior tip of occipital lobe Receives visual information from retinas

Motor areas

Primary motor cortex

Premotor cortexFrontaleye fieldBroca's area(outlined by dashes)

Working memoryfor spatial tasks

Executive area fortask management

Working memory for object-recall tasksSolving complex,multitask problems

Prefrontal cortex

Lateral view, left cerebral hemisphere

Sensory areas and relatedassociation areasPrimary somatosensorycortexSomatosensoryassociation cortex

Gustatory cortex(in insula)

Somatic sensation

Taste

Wernicke's area(outlined by dashes)

Primary visualcortexVisualassociation area

Auditoryassociation area

Primary auditory cortex

Vision

Hearing

Central sulcus

Primary motorcortex

Motor associationcortex

Primary sensorycortex

Sensoryassociation cortex

Multimodal associationcortex

Auditory AreasPrimary auditory cortex

Superior margin of temporal lobes Interprets information from inner ear as pitch,

loudness, and location

Motor areas

Primary motor cortex

Premotor cortexFrontaleye fieldBroca's area(outlined by dashes)

Working memoryfor spatial tasks

Executive area fortask management

Working memory for object-recall tasksSolving complex,multitask problems

Prefrontal cortex

Lateral view, left cerebral hemisphere

Sensory areas and relatedassociation areasPrimary somatosensorycortexSomatosensoryassociation cortex

Gustatory cortex(in insula)

Somatic sensation

Taste

Wernicke's area(outlined by dashes)

Primary visualcortexVisualassociation area

Auditoryassociation area

Primary auditory cortex

Vision

Hearing

Central sulcus

Primary motorcortex

Motor associationcortex

Primary sensorycortex

Sensoryassociation cortex

Multimodal associationcortex

OIfactory CortexPrimary olfactory (smell) cortex

Medial aspect of temporal lobes (in piriform lobes)

Motor areas

Primary motor cortex

Premotor cortexFrontaleye fieldBroca's area(outlined by dashes)

Working memoryfor spatial tasks

Executive area fortask management

Working memory for object-recall tasksSolving complex,multitask problems

Prefrontal cortex

Lateral view, left cerebral hemisphere

Sensory areas and relatedassociation areasPrimary somatosensorycortexSomatosensoryassociation cortex

Gustatory cortex(in insula)

Somatic sensation

Taste

Wernicke's area(outlined by dashes)

Primary visualcortexVisualassociation area

Auditoryassociation area

Primary auditory cortex

Vision

Hearing

Central sulcus

Primary motorcortex

Motor associationcortex

Primary sensorycortex

Sensoryassociation cortex

Multimodal associationcortex

Gustatory Cortex In insula just deep to temporal lobe

Involved in perception of taste

Corpuscallosum

Frontal eye field

Prefrontalcortex

Processes emotionsrelated to personaland social interactions

Orbitofrontalcortex

Olfactory bulb

Olfactory tract

FornixTemporallobe

Primaryolfactorycortex

Uncus

Calcarine sulcus

Parahippocampalgyrus

Parietal lobe

Somatosensoryassociation cortex

Parieto-occipitalsulcus

Occipitallobe

Visual associationarea

Primaryvisual cortex

Primary somatosensorycortex

Central sulcusPrimarymotor cortex

Cingulategyrus

Premotorcortex

Parasagittal view, right cerebral hemisphere

Primary motorcortex

Motor associationcortex

Primary sensorycortex

Sensoryassociation cortex

Multimodal associationcortex

Limbic System: Emotion and CognitionReact emotionally to things we consciously

understand to be happening

Consciously aware of emotional richness in our lives

Hippocampus and amygdaloid body—play a role in memory

Septum pellucidum

Fiber tracts connectinglimbic system structures

FornixAnterior commissure

Cerebral structures of the limbic system

Cingulate gyrusSeptal nucleiAmygdaloid body

Hippocampus

Diencephalic structures of the limbic system

Anterior thalamicnuclei (flanking3rd ventricle)

Hypothalamus

Mammillary body

Olfactory bulb

Corpus callosum

• Dentate gyrus• Parahippocampal gyrus

Reticular Formation: RAS and Motor Function

Reticular activating system (RAS) Sends impulses to cerebral cortex to keep it

conscious and alert Filters out repetitive, familiar, or weak stimuli

(~99% of all stimuli!) ADHD

Inhibited by sleep centers, alcohol, drugs Severe injury results in permanent

unconsciousness (coma)

Visualimpulses

Reticular formation

Ascending generalsensory tracts(touch, pain, temperature)

Descendingmotor projectionsto spinal cord

Radiationsto cerebralcortex

Auditoryimpulses

Protection of the BrainBone (skull)

Membranes (meninges)

Watery cushion (cerebrospinal fluid)

Blood brain barrier

MeningesCover and protect CNS

Protect blood vessels and enclose venous sinuses

Contains cerebrospinal fluid (CSF)

Forms partitions in skull

MeningesThree layers

Dura mater Arachnoid mater Pia mater

Meningitis Inflammation of meninges

Skin of scalpPeriosteum

Bone of skullDura mater• Periosteal layer• Meningeal layer

Arachnoid materPia materArachnoid villusBlood vessel

Falx cerebri(in longitudinalfissure only)

Superior sagittalsinus

Subduralspace

Subarachnoidspace

Dura Mater Strongest layer

Arachnoid MaterMiddle layer with weblike extensions

Separated from dura mater by subdural space

Subarachnoid space contains CSF and largest blood vessels of brain

Arachnoid villi protrude into superior sagittal sinus and permit CSF reabsorption

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Skin of scalpPeriosteum

Bone of skullDura mater• Periosteal layer• Meningeal layer

Arachnoid materPia materArachnoid villusBlood vessel

Falx cerebri(in longitudinalfissure only)

Superior sagittalsinus

Subduralspace

Subarachnoidspace

Pia MaterDelicate vascularized connective tissue that

clings tightly to brain

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